Brake



Nov. 18,1941. A. Y, DODGE 2,263,263

BRAKE Filed March 28-, 1938 a Sheets-Sheet 1 Nov. 18, 1941.

'A. Y. DODGE BRAKE 3 Sheets-Sheet 2 Filed March 28, 1938 pwa II FIIIIIIII 'II Nov..18, 1941.- Y. DODGE BRAKE Filed March 28, 1938.

s Sheets-Sheet s Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE Adlel Y. Dodge, Rockford, Ill. Application March 28, 1938, No. 198,378

My invention relates to brakes.

One of the objects of my invention is to pro-- vide such a brake construction in which the initial take-up movement of the actuating band is effected by a relatively high speed hydraulic transmission between the brake pedal and the hydraulic band actuator and in which the final pressure applying movement of the actuating band is effected by a relatively low speed hydraulic transmission between the brake pedal and the hydraulic band actuator.

A further object of my invention is to provide such a construction in which, in case the low speed transmission fails in applying the braking pressure, the high speed transmission. will be effective for this purpose.

I am aware that there have been previous attempts to accomplish some of these objectives. However, it is naturally out of the question to use any brake control apparatus. which brings about a sudden change of application of pressure.

Further objects and advantages of the invention will be apparent from the description and claims. Y In the drawings, in which several embodiments of my invention are shown,

Figure l-is an axial section showing construction and associated parts;

Fig. 2 is a transverse section substantially o'n the line 2- 2 of Fig. 1; 4

, Fig. 3 is an enlarged axial section showing the brake-drum and backing plate;

the brake plate.

Fig. 4 is a sectionalview substantially on the 7 line 4-4 of Fig. 3;

Fig, 5 is a detail view showing the actuating and;

Fig. 6isa diagrammatic view showing a hydraulic actuator for supplying fluid pressure to the brake cylinder;

Fig. '7 is a diagrammatic view showing another form of hydraulic actuator;

Fig. 8 is a diagrammatic view showing another form of hydraulic actuator; and

Fig. 9 is a diagrammaticsectional view showing another form of hydraulic actuator.

Referring first to Figs. 1 to 5, inclusive, the construction shown comprises an axle lwhic-h may be the axle of an automobile, a portion of one of the wheels 2 mounted on this axle to rotate therewith, a brake drum 3 having an internal braking surface 4 secured to this wheel, 2, a backing plate 5 having a cylindrical band-supporting surface .6 secured to a nonrotatable part of the automobile such as the housing 'I for the bearings 5 Claims. (Cl. 60-54-5) backing plate 5, a flexible metal cylindrical expansible band 9 extending around the major portion of the cylindrical supporting surface 6' the band 9 circumferentially away from the stationary end of the band, and means for holding the flexible brake band members Ill against circumferential movement with respect to the cylindrical supporting surface 6.

The wheel and axle construction may be of any suitable type, that shown comprising suitable anti-friction bearings l2 by means of which the axle l and wheel 2 are rotatably mounted in the nonrotatable housing member 1. The expansible band 9 and the arcuate brake band members I0 are held in place against excessive lateral movement between the flange l3 on the backing plate 5 and the guard plate 8 secured to the backing expansible band against circumferential movement comprises an abutment member l4 struck up from the material of the backing plate and extending through andfitting fairly closely in,

members against circumferential movement comprise, in addition to the abutment member H, a number of other abutment members l6 and I! also struck up from the material of the backing plate 5, theseabutment'members l4, l6, and Il being engageable by the ends of the segmental brake band members l0 which are held by said abutment members against any substantial circumferential movement. The segmental brake .band members are secured to the flexible expansible band by means of tongues 18 struck up from the metal reinforcing plates l9 of'the brake band members and extending through corresponding registering openings 20 in the expansible band 9, and washers 2| through which the ends of the tongues extend, the washers being held ln'place, on the tongues in any suitable manner as by means of pins .22 extending through the tongues 18 and engaging the washers 2 I.

Each segmental brake band member comprises,

7 in addition to the sheet metal reinforcing plate for the axle l, a guard member 8 secured to this IS, a flexible brake lining member 23 secured to The means for holding one end of thethe backing plate in any suitable manner, as by rivets 24 or the like. A clearance is provided between the tongues I8 and the edges of the openings 20 in the expansible band to provide for the necessary relative movement between the expansible band and brake band members, as shown in Fig. 4.

The actuating expansible band is provided with suitable openings l5 through which the abutment members extend, all of the openings being provided with a clearance, as shown in Fig. 2, to enable the expanding action of the expansible band. For expanding the band, any suitable actuator may be provided, that shown comprising. a hydraulic cylinder Ii mounted on the backing plate 5 and having a hydraulically actuated plunger 25 engaging an abutment member 26 secured to and adjacent one end of the expansible band 9. The other end of the expansible band may be provided with a suitable abutment member 21 engaging a fixed portion on the casing of the hydrauliccylinder II. A suitable coil tension spring 23 may be provided for contracting the expansible band when the hydraulic pressure is released.

As the band 9 contracts, it will carry with it the segmental brake band members In which, as previously described, are secured to the expansible band. With this construction, it will be seen that as the expansible band 9 contracts, it will wrap smoothly into cylindrical shape about the cylindrical supporting surface 6 of the backing plate 5 and thus the expansible band 3 and the brake band members In carried thereby'will be supported in coaxial relation with respect to the inner cylindrical braking surface 4 and out of contact therewith. This will cause the braking surface of the segmental brake band members Hi to be uniformly spaced from the cylindrical braking surface 4 throughout their entire extent when the flexible expansible band 9 is wrapped snugly about the cylindrical surface 8 of the backing plate. It will also be seen that in use when the brakes are applied, the flexible brake band members-J0 will have a self-energizing action constituting in effect three flexible, segmental, arcuate brake band members, each having the brake band members.

It will be noted that I have shown no-provision for take-up or adjustment between the hydraulic which it closely hugs the cylindrical surface 6 of the backingplate 5 to its extremely expanded position in which the brake band members iii are pressed snugly into engagement with the cyli ndrical braking surface 4.

Assuming that the brake band members will .wear down sixty-thousandths (.060) of an inch and that it may be desirable to have a ten-thousandths (.010) of an inch clearance between the unwom brake band members I! and the cylindri cal braking surface 4 when the expansible band 3 is fully contracted, it will be seen that the dimeter of the expansible band will have to change at least one-hundred-for'ty-thousandths (.140) of an inch from its fully contracted condition to its fully expanded condition,'when the brake band members it are worn thin. This requires a substantial movement of the plunger 25 of the hydraulic actuator H, a large portion of which movement is expended simply in moving the actuating band 9 from its fully-contracted condition to an expanded condition in which it just begins-to exert braking pressure. The motion of the plunger 25 of the hydraulic actuator may thus be divided into two parts, the first part of the movement being simply to expand the expansible band 9 against the contractile forces,

due to its inherent contractile condition and to the contractile efiect of the tension spring 28, and the second part of the movement being that in which braking pressure is exerted to press the brake band members l0 against the cylindrical braking surface 4. The first part of this movement requires a relatively small force, whereas the second part of the movement may require a very considerable force to cause the desired braking effect.

In order to secure this relatively large movement of the hydraulic actuator, I provide hydraulic transmission between the brake pedal or brake actuator and the hydraulic cylinder I I by means of which the first part of the movement of the pedal or brake actuator will cause a relatively large and rapid movement of, the plunger 25 of the expansible band actuator and whereby the latter part of the movement of the brake pedal or the brake actuator will cause a relatively short, slow and forceful action of the plunger 25 of the actuator for the expansible band. I also provide means whereby if that part of the hydraulic transmission which supplies the slow, forceful action of the band actuator fails, the other relatively rapid, low force part of the transmission may be used asan emergency apparatus to cause the application of brake pressure.

The construction shown in Fig.- 6 comprises a fluid conduit 29 connected with the cylinder of the expansible band actuator I I, a relatively large diameter low pressure cylinder 30 connected with this conduit by a conduit 3|, a relatively small diameter, high pressure cylinder 32 connected with the conduit 29 by a conduit 33, a check valve 34 in the conduit from the low pressure cylinder to the conduit, permitting flow in the direction of-the arrow from the cylinder 30 to the conduit 29 but preventing flow in the reverse direction, a fluid reservoir 35 connected with the low pressure cylinder 30 by a conduit 36, a conduit 31 connecting the low pressure cylinder 30 with the high pressure cylinder 32, a piston 30 operating in the low pressure cylinder 30, a piston 39 operating in the high pressure cylinder 32, a reciprocable plunger 40 connected with the brake pedal or brake actuatoi', an equalizer bar 4| pivotally connected at 42 with the reciprocable plunger 40 and having pin and slot connections 43 with the piston rods of the high and low pressure pistons, respectively, and spring means 0pposing resistance to the movement of the arm of the equalizer bar connected with the highpressure piston rod.

Suitable bleed connections 44 may be provided for the high and low pressure cylinders, which bleed connections may, if desired, lead to the reservoir.

In-using this transmission, the first part of the movement of the reciprocable plunger 40 will cause movement of the low pressure piston 33 only, since'movement 01' the high pressure piston is opposed by the action of the springs 45 and 46. it will be seen that the only resistance to the movement of the low pressure piston 33 is that of the fluid in the cylinder 33 acting on the relatively large exposed surface of the piston but that the forces opposing movement of the high pressure piston 39 include, in addition to the pressure of the fluid in the cylinder acting on the relatively small surface of the piston, the action of the springs 43 and 43 which also oppose movement of the piston. As the eifective lever arms of the equalizer 4i acting on the piston rods 41 and 43 are substantially equal, it will be seen that as the brake-actuating slide 43 is moved, one of the pistons will be actuated which opposes the least resistance to movement. It will also be seen that so long as the low pressure cylinder is moving and causing fluid to flow through the conduit, the pressure in the two cylinders will be substantially the same, as the two cylinders are then in communication with each other through the conduits 3| and 33. Under these conditions, the force opposing motion of the large piston 33 will be the area of this piston times the unit pressure of the fluid, and the force opposing motion'of the high pressure piston 33 will be the area of the small piston, times the unit area fluid pressure, plus the two spring resistances 43 and 43. It will be seen that an increase in fluid pressure will have a much greater resisting effect on the larger piston than on the smaller piston, that this differential increase in resisting eifect will eventualincrease, due to the increased resistance to furcrank lever being pivotally mounted at 53. As the high pressure piston 33 moves to the right, the roller 3! on the equalizer lever will roll along the arm of they bell crank'lever, thus changing the angle of the surface engaging the roller and changing the effective lever arm of that arm of the bell crank engaging the roller, thus opposing a gradually decreasing resistance to the movement of the high pressure piston". It will be noticed that in the shift of movement from the low pressure piston 33 to the high pressure piston 39, a point of equilibrium is reached and passed so that the low pressure piston will come to rest gradually and the high pressure piston will start to move gradually.

When it is desired torelease the brake, the brake-actuating slide 40 is allowed to move to the left, as viewed in Fig. 6, under the action of a suitable spring 45. This movement of the slide will first cause the high pressure. piston-:39 to fluid to flow from the band actuator ll through" the conduits 23 and 33 into the high pressure cylinder 32 and thence through the conduit 31 into the low pressurecylinder 33, enabling the low pressure piston 33 to return to the position shown in Fig. '6.

The construction shown in Fig. 7 is similar to that of Fig. 6, including the following parts: the conduit 29, the lowpressure cylinder 30, the conduit 3|, the high pressure cylinder 32, the conduit 33, the check valve 34, the reservoir, the conduits 36 and 31, the low pressure piston 33, the

low pressure piston .33 is greater than the opposition to movement of the high pressure piston 38, caused by the pressure on the relatively small piston and the action of the springs and 43.

the low pressure piston 33 will gradually be brought to a standstill and the high pressure piston 33 will gradually begin to move. This will enable a relatively slow but forceful action to be exerted on the hydraulic actuator. During the movement of the high pressure piston 33, the check valve 34 .will close, preventing fluid from flowing from the high pressure cylinder .into the low pressure cylinder. The movement of the high to eifect the flnal movement of the brake band members.

It will be noted that one of the springs 43 upposes a variable resistance to the motion of the high pressure piston 33. This is accomplished by connecting the spring at one end to a flxed support 43 and at the other end to a bell crank lever 33, one arm of which is engaged by a roller 3| on the end of. the equalizer lever 4|, the bell high pressure piston 33, the push rod 43, the

equalizer bar 4|, the pivotal connection 42, the

pin-and-slot connection 43, the vents 44, the springs 43 and 43, the piston rods 41 and 43, the fixed support 43, the bell crank lever 50, the roller 5|, and the pivotal mounting 52. The operation of the above parts is similar to the operation of the corresponding parts in Fig. 6. This construction, however, comprises in addition a pneumatic booster for the pedal-actuated slide. This pneumatic booster comprises a power cylinder 53 and a power piston having a piston rod 54 connected by an arm 53 with the pistonrod 41 of the low pressure cylinder 30. This pneumatic boosteris con- .trolled by the valve mechanism having a valve 53 which in one position may connect the power cylinder 53 with the engine intake manifold connection 51 and which in another position connects the power cylinder 53 with the discharge connection 53. This valve .mechanism is controlled by a cam member 59 secured tothe valve stem 33, which cam member is depressed by a cam member 3| onthe pedal-actuated rod 43. A coil algebraic sum of the forces acting to move the high pressure piston to the right is greater than the algebraic sum of the forces acting to move the low pressure piston to the'right, the high pressure piston will be the one which moves.

The purpose of the'vacuum booster cylinder is to actuate the low pressure hydraulic cylinder with just suflicient force to cause a very mild amount of braking action or deceleration. In this construction the only energy which the high pressure cylinder must transmit is that necessary to increase the degree of braking (that is, to increase the force of movement necessary to follow up deflections and drum expansion). Thus the leverage employed between the brake pedaland the band actuating cylinder H may be increased so that a good muscular efiort will suflice to decelerate a heavier vehicle than would otherwise be possible.

As indicated above the force exerted by the vacuum booster cylinder 53 may be relatively slight. When the forces exerted on the piston rod H by the lever 4! and by the vacuum booster conduit 63 leading to the cylinder of the band actuator II, a low pressure cylinder 88 for causing the initial movement of the band actuator H, a high pressu e cylinder 65 for causing the final movement of the band actuator, and a relatively large hydraulic cylinder 68 for actuating the ,piston 81 of the high pressure cylinder 65. A

check valve 88 is provided in the conduit 68 leading from the low pressure cylinder 84 to the conduit 63 leading to the band actuator ll, permitting flow. from the cylinder 64 to the conduit 63 but preventing return flow. A check valve 88::

- is provided in a conduit 18 leading from' the reservoir H to the discharge end of the low pressure cylinder 64 permitting fluid to flow from the reservoir II into the low pressure cylinder but preventing return flow. A conduit I2 is provided leading from the high pressure cylinder 85 to the conduit 68 leading to the band actuator II. A conduit 13 is provided from the low pressure cylinder 84 to the actuator cylinder 68. A pressure-actuated valve II is provided in this passage which will open to enable fluid to flow from the low pressure cylinder 64 to the actuator cylinder 88 only when the pressure reaches a flow from the actuator cylinder 66 into the low pressure cylinder 84 but prevents flow from the low pressure cylinder into the actuator cylinder. A conduit 18a is provided leading from the reservoir H to keep the cylinder full of fluid, a suitable check valve being provided to prevent flow from the cylinder 66 to the reservoir.

In order to enable the low pressure piston 18 to complete its movement to the left when the brake pedal is released, the conduit Ill is provided between the reservoir ill and the right-hand end of the low pressure cylinder 84 provided with the check valve 88 which will enable fluid to flow from the reservoir into the low pressure cylinder but which will prevent flow from the low pressure cylinder into the reservoir. The check valve 68 is provided in the passage leading from the low pressure cylinder to the band actuator H which will permit fluid to flow from the low pressure cylinder to the band actuator but will prevent flow from the high pressure cylinderGS back into the low pressure cylinder 64.

With this construction, initial movement of the push rod 8B will move the low pressure piston 'IB to the right, causing fluid to flow through the conduit 68 into the cylinder H of the band actuatorto eifect a rapid relatively large movepredetermined amount. A by-pass conduit 15 is in this by-pass conduit Ii which enables fluid to ment of the plunger of the band actuator ll. When the resistance to movement of the band actuator increases to an extent to raise the pressure in the line, the spring-pressed valve M controlling communication between the low pressure cylinder 64 and the actuator cylinder 86 will be forced open and pressure will be exerted on the actuator piston H to move the high pressure piston 61 to theright, thus causing a powerful slow motion action of the bandactuator II to cause the final braking action.

When the push rod 88 is released,'the high pressure piston 61 will move to the left because of the action of the coil compression spring 18 and the pressure of the fluidon the high pressure piston. This will force fluid from the actuator cylinder 66, through the by-pass conduit 15, past the check valve 18, and through the conduit 13 into the low pressure cylinder 6!. When the actuator piston 11 has moved to its extreme lefthand position, as shown in Fig. 8, the low pressure piston 18 will continue to move to the left under the action of a suitable return spring (not shown), fluid being withdrawn from the reservoir II, through the conduit 18, past the check valve88, and into the low pressure cylinder 84.

In Fig. 9 the construction shown comprises a conduit 8| leading to the band actuator II, a high pressure cylinder 82 in communication with this conduit 8|, through the conduit 83, a low pressure cylinder 84 in communication with the conduit 8!, through the conduits 85 and 88 and past the check valve 81, a reservoir 88 in communication with the low pressure cylinder 84, through the conduit 88 and through the conduits 88 and 8|, past the check valve 92, a spring-' pressed pressure-controlledvalve 83 controlling.

communication between the low pressure cylinder 84 and the reservoir 88, pistons 84 and 88 for the high and low pressure cylinders, respectively,

and piston rods 88 and 81 for these cylindersrigidly connected to the piston rods. During the first part or the movement 0! the crosshead. fluid will be supplied to the band actuator ll sure of the fluid on the piston Hill which carries the valve tlii will assist inholding the valve 93 open against the pressure of the spring ii. A

bleed vent M32 is provided in this piston to permit the passage of fluid therethrough from the low pressure cylinder into the reservoir.

After the low pressure cylinder M ceases to supply fluid to the band actuator II, the high pressure cylinder 83 will continue to supply fluid to effect the final braking movement.

Further modifications will be apparent to those the inventionbe limited only by the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A fluid power transmission apparatus comprising an actuating member, a fluid motor, and

, transmission between said actuating member and said movement the high displacement pump will supply none or a relatively small proportion of the fluid supplied to the motor and the :low dis placement pump will supply all or a relatively large proportion of the fluid supplied to the motor, said means including power-transmitting instrumentalities acting between said actuating member and pumps, respectively, and including also yieldable variable resistance means opposing movement of said low displacement pump with a force which decreases gradually with the movement of said low displacement pump whereby at approximately theposition in which the high displacement pump lessens its proportion of fluid supply to the motor the ratio of power transmitted to the motor with respect to power supplied to the actuating member is relatively low and whereby as movement of the actuating member continues said ratio increases.

2. A fluidpower transmission apparatus comprising an actuating member, a fluidmotor, and transmission between said actuating member and motor comprising a high displacement pump and a low displacement'pump, both supplying fluid to said motor, means whereby, as the actuating member is moved during an early part of said movement, the high displacement pump will supskilled in the art and it is desired, therefore, that ply all or a relatively large proportion of the fluid supplied to said motor and during a. later part of said movement the high displacement pump will supply none or a relatively small proportion of. the fluid supplied to the motor and the low displacement pump will, supply all or a relatively large proportion ofthe fluid supplied to the motor, said means including power-transmitting instrumentalities acting between said actuating member and pumps, respectively, and

including also yieldable resistance means opposing initial movement of said low displacement pump whereby at approximately the position in which the high displacement pump lessens its proportion of fluid supply to the motor the ratio of power transmitted to the motor with respect to power supplied to the actuating member is relatively low and whereby as movement of the actuator continues. said ratio increases, said yieldable resistance means comprising a springpressed lever whose lever arm ratio changes a the low displacement pump moves.

3. In an hydraulic brake applying apparatus a high displacement low pressure cylinder and-piston, a low displacement high pressure cylinder and piston, and means for actuating said pistons and controlling their movement, said actuating means comprising a common actuator tor said pistons, said movement-controlling means comprising a resistance gradually decreasing as the low displacement piston moves, said resistance opposing movement of said low displacement piston and preventing movement of said low displacement piston until the high displacement piston has created a pressure resistance to its movement sumcient to cause the force applied to the low displacement piston to overcome the opposing gradually decreasing resustance.

a. In an hydraulic brake actuating trasion, the combination oi a pedal, a low pressure chamber, a high pressure chamber and pressure actuators, force-transmitting and dividing means v chamber, a high'pressure chamber and pressure actuators, a force-transmitting and dividing means connecting the low and high pressure actuators to the pedal, yieldahle and decre resistance means acting to resist the high'pressure actuator with continually decreasing resistance after a. predetermined press has been reached, and means to stop movement of the high pressure actuator prior to the end of pedal travel and prior tothe end or travel of the lowpressure actuator.

-, W. Y DODGE. 

